Developmental trajectories of clinically significant attention-deficit/hyperactivity disorder (ADHD) symptoms from grade 3 through 12 in a high-risk sample: Predictors and outcomes

The influence of comorbid asthma on the severity of symptoms in children with attention-deficit hyperactivity disorder

OBJECTIVE

The current study examined the association between asthma and attention-deficit hyperactivity disorder (ADHD) symptoms in a clinical pediatric sample.

METHODS

Demographic and neuropsychological data for children with a billing diagnosis of ADHD were extracted from a clinical database. Families completed standard rating scales. Seventy-one patients with a co-morbid asthma diagnosis were identified and matched by age to a group of 71 patients with only ADHD.

RESULTS

Children with asthma and ADHD were more likely to display clinically elevated levels of hyperactivity, externalizing behaviors, anxiety, and hyperactive/impulsive behaviors compared to children with ADHD alone. Boys with asthma and ADHD had more symptoms than boys with only ADHD of somatization and emotional internalizing, while girls with asthma and ADHD had more symptoms of hyperactivity/impulsivity, conduct problems, anxiety, and emotional internalizing compared to girls with only ADHD.

CONCLUSIONS

Findings suggest that in children with ADHD, co-morbid asthma is associated with increased behavioral and internalizing symptoms, with distinct gender differences present. Increased behavioral and internalizing symptoms seen in children with both asthma and ADHD may be due to the burden of their medical condition. No difference was found on cognitive variables, suggesting chronic hypoxia may be less influential in explaining these differences. Future research should determine the specific mechanisms of these differences.

Trait Impulsivity and the Externalizing Spectrum

This article reviews evidence that trait impulsivity-expressed early in life as the hyperactive-impulsive and combined presentations of attention-deficit/hyperactivity disorder (ADHD)-is a bottom-up, subcortically mediated vulnerability to all externalizing disorders. This vulnerability arises from deficient mesolimbic dopamine responding, which imbues psychological states (irritability, discontentment) that motivate excessive approach behavior (hyperactivity, impulsivity). Through complex interactions with (a) aversive motivational states that arise from largely independent subcortical systems, (b) emotion regulatory mechanisms that arise from top-down, cortical modulation of subcortical neural function, and (c) environmental risk factors that shape and maintain emotion dysregulation, trait impulsivity confers vulnerability to increasingly severe externalizing behaviors across development. This perspective highlights the importance of identifying transdiagnostic neural vulnerabilities to psychopathology; dovetails with the hierarchical, latent structure of psychopathology; and suggests that progression along the externalizing spectrum is an ontogenic process whereby a common, multifactorially inherited trait interacts with endogenous and exogenous influences to yield increasingly intractable externalizing behaviors across development.

Prefrontal and parietal correlates of cognitive control related to the adult outcome of attention-deficit/hyperactivity disorder diagnosed in childhood

The protracted and highly variable development of prefrontal cortex regions that support cognitive control has been purported to shape the adult outcome of attention-deficit/hyperactivity disorder (ADHD). This neurodevelopmental model was tested in a prospectively followed sample of 27 adult probands who were diagnosed with ADHD in childhood and 28 carefully matched comparison subjects aged 21-28 years. Probands were classified with persistent ADHD or remitted ADHD. Behavioral and neural responses to the Stimulus and Response Conflict Task (SRCT) performed during functional magnetic resonance imaging (fMRI) were compared in probands and comparison subjects and in probands with persistent and remitted ADHD. Response speed and accuracy for stimulus, response, and combined conflicts did not differ across groups. Orbitofrontal, inferior frontal and parietal activation was lower in probands than comparison subjects, but only for combined conflicts, when demand for cognitive control was highest. Reduced activation for combined conflicts in probands was almost wholly attributable to the persistence of ADHD; orbitofrontal, inferior frontal, anterior cingulate and parietal activation was lower in probands with persistent ADHD than both probands with remitted ADHD and comparison subjects, but did not differ between probands with remitted ADHD and comparison subjects. These data provide the first evidence that prefrontal and parietal activation during cognitive control parallels the adult outcome of ADHD diagnosed in childhood, with persistence of symptoms linked to reduced activation and symptom recovery associated with activation indistinguishable from adults with no history of ADHD.

Life Span Studies of ADHD-Conceptual Challenges and Predictors of Persistence and Outcome

There is a renewed interest in better conceptualizing trajectories of attention-deficit/hyperactivity disorder (ADHD) from childhood to adulthood, driven by an increased recognition of long-term impairment and potential persistence beyond childhood and adolescence. This review addresses the following major issues relevant to the course of ADHD in light of current evidence from longitudinal studies: (1) conceptual and methodological issues related to measurement of persistence of ADHD, (2) estimates of persistence rate from childhood to adulthood and its predictors, (3) long-term negative outcomes of childhood ADHD and their early predictors, and (4) the recently proposed new adult-onset ADHD. Estimates of persistence vary widely in the literature, and diagnostic criteria, sample characteristics, and information source are the most important factors explaining variability among studies. Evidence indicates that ADHD severity, comorbid conduct disorder and major depressive disorder, and treatment for ADHD are the main predictors of ADHD persistence from childhood to adulthood. Comorbid conduct disorder and ADHD severity in childhood are the most important predictors of adverse outcomes in adulthood among children with ADHD. Three recent population studies suggested the existence of a significant proportion of individuals who report onset of ADHD symptoms and impairments after childhood. Finally, we highlight areas for improvement to increase our understanding of ADHD across the life span.